Carbon dioxide conversion and purification equipment and method based on membrane separation

Abstract

The invention discloses carbon dioxide conversion and purification equipment and method based on membrane separation, and relates to the technical field of gas conversion and purification. Comprising a waste gas inlet pipe and a controller, one side of the waste gas inlet pipe is fixedly communicated with a gas inlet header pipe, one side of the gas inlet header pipe is fixedly communicated with at least one gas inlet branch pipe, and gas outlets of the gas inlet branch pipes are connected with a carbon dioxide separation device. The device is provided with a plurality of carbon dioxide separation devices, each carbon dioxide separation device comprises a first separation membrane and a second separation membrane, the first separation membrane adsorbs other gases except carbon dioxide gas in waste gas and allows the carbon dioxide gas to pass through, and the second separation membrane only allows the carbon dioxide gas to pass through. According to the device, carbon dioxide is separated from the tail gas, other gases are blocked, and the residual tail gas is treated while the carbon dioxide is separated, so that the residual tail gas can be treated without additionally arranging a tail gas treatment device, the occupied area of the device is small, and the investment and operation costs are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of gas conversion and purification, and in particular to a carbon dioxide conversion and purification device and method based on membrane separation. Background Art

[0002] The high-temperature flue gas from the combustion device contains greenhouse gas carbon dioxide and various gaseous pollutants, such as hydrocarbons, carbon monoxide and nitrogen oxides. In order to achieve low-carbon, energy-saving and environmentally friendly emission requirements, it is necessary to treat the carbon dioxide and pollutants in the flue gas. Converting and purifying carbon dioxide through membrane separation technology is one of the treatment methods.

[0003] The Chinese invention patent, application publication number CN114377514A discloses a carbon dioxide capture and conversion integrated continuous production device and method. The carbon dioxide capture and conversion integrated continuous production device is used to switch between modes A and B to achieve continuous production at the same temperature without temperature change operation, and the product is continuously collected without desorption, which effectively simplifies the carbon dioxide capture and conversion process, reduces the energy consumption of carbon dioxide disposal, and significantly improves the reaction efficiency.

[0004] For example, the Chinese invention patent, application publication number CN118454684A discloses an integrated flue gas carbon dioxide capture and conversion method that coordinates CO, HC, and NOx catalytic purification, which realizes the resource utilization of the captured CO2. The entire reaction can be achieved in the same device, which has the functions of CO2 capture and pollutant purification at the same time, and the system is simple and compact.

[0005] The above scheme and the prior art still have certain defects in the practical application of carbon dioxide conversion and purification equipment, such as: 1. Carbon dioxide in the exhaust gas is captured by a separation membrane, and the remaining exhaust gas needs to be treated again by an exhaust gas treatment device, resulting in a large footprint for production equipment and increased investment and operating costs.

[0006] 2. The existing technology separates carbon dioxide from exhaust gas through membrane separation technology, while the remaining exhaust gas is absorbed, converted or blocked by the membrane. Certain components in the exhaust gas may react chemically with the membrane material, causing changes in the chemical properties of the membrane material, thereby reducing the separation performance and stability of the membrane. Chemical corrosion will intensify under long-term operation and eventually lead to membrane damage. Replacing the separation membrane inevitably requires shutdown, thereby reducing the system's working efficiency.

[0007] 3. During the production process, with the change of fuel and the adjustment of operating conditions, the exhaust gas flow rate and the carbon dioxide concentration in the exhaust gas may change. In this way, the following defects will occur according to the fixed hydrogen addition ratio, that is, if the carbon dioxide concentration decreases and the hydrogen supplement amount remains unchanged, it may lead to hydrogen waste; on the contrary, if the carbon dioxide concentration increases and the hydrogen supplement amount is insufficient, it may affect the separation effect and reduce the carbon dioxide conversion amount. Summary of the invention

[0008] The object of the present invention is to provide a carbon dioxide conversion and purification device and method based on membrane separation to solve the problems raised in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a membrane separation-based carbon dioxide conversion and purification device, comprising an exhaust gas inlet pipe and a controller, wherein one side of the exhaust gas inlet pipe is fixedly connected to an intake manifold, one side of the intake manifold is fixedly connected to at least one intake branch pipe, and the outlet of the intake branch pipe is connected to a carbon dioxide separation device; After being dried, degreased and heated, the exhaust gas enters the carbon dioxide separation device through the exhaust gas inlet pipe, the intake manifold and the intake branch pipe, and the carbon dioxide in the exhaust gas is separated by the carbon dioxide separation device; The separated carbon dioxide enters the gas outlet main pipe and the gas outlet main pipe through the gas outlet branch pipe. The gas outlet main pipe is connected to the carbon dioxide converter. A hydrogen inlet pipe is provided on one side of the carbon dioxide converter. A hydrogen generator is connected to one side of the hydrogen inlet pipe. The catalyst in the carbon dioxide converter converts the carbon dioxide and hydrogen entering the carbon dioxide converter. One side of the carbon dioxide converter is fixedly connected with a product outlet pipe, one side of the product outlet pipe is fixedly connected with a cooler, one side of the cooler is connected with a gas-liquid separator through a first connecting pipe, one side of the gas-liquid separator is connected with a distiller through a second connecting pipe, and the distiller is respectively fixedly connected with a first product outlet pipe and a second product outlet pipe; The pipe body of the gas outlet main pipe is connected with a carbon dioxide detection spectrometer, and the pipe body of the hydrogen inlet pipe is connected with a flow meter and a third electromagnetic valve.

[0010] Furthermore, the carbon dioxide separation device comprises a first tank body and a second tank body that are detachably fixed together, and a first separation membrane and a second separation membrane are respectively arranged in the first tank body and the second tank body; The first separation membrane adsorbs the remaining gases in the exhaust gas except carbon dioxide, and allows carbon dioxide to pass through. The second separation membrane only allows carbon dioxide to pass through, and blocks other gases. A second solenoid valve is connected to the top of the second tank body, and a top tube and a bottom tube are fixedly connected to one side of the first tank body and the second tank body respectively. The top tube and the bottom tube are detachably fixed, and a first solenoid valve is connected to the tube body of the bottom tube.

[0011] Furthermore, the top of the second tank body is fixedly connected with a pressure relief branch pipe, one side of the pressure relief branch pipe is fixedly connected with a pressure relief main pipe, and the pressure relief main pipe is fixedly connected with the exhaust gas inlet pipe through a third connecting pipe; The pipe body of the pressure relief branch pipe is connected with a fifth solenoid valve, and the top of the second tank body is connected with a second pressure sensor.

[0012] Furthermore, the top of the gas-liquid separator is fixedly connected to an excess hydrogen outlet pipe, and a first one-way valve is connected to the pipe body of the excess hydrogen outlet pipe, so that the excess hydrogen generated by conversion and purification enters the hydrogen inlet pipe through the excess hydrogen outlet pipe; The gas outlet of the excess hydrogen outlet pipe is located between the third solenoid valve and the hydrogen generator.

[0013] Furthermore, a mixing tank is provided between the gas outlet main pipe and the carbon dioxide converter, the gas outlet main pipe and the hydrogen inlet pipe are fixedly connected to the mixing tank respectively, and the mixing tank is fixedly connected to the carbon dioxide converter through the mixed gas outlet pipe; A stirring element is provided in the mixing tank, and the hydrogen and carbon dioxide gases in the mixing tank are mixed by the stirring element to prevent the hydrogen and carbon dioxide gases from being stratified.

[0014] Furthermore, a pressure stabilizing component is provided on one side of the exhaust gas inlet pipe, and the gas pressure in the exhaust gas inlet pipe is kept constant by the pressure stabilizing component.

[0015] Furthermore, the voltage stabilizing component includes a boost pipe fixedly connected to the exhaust gas inlet pipe, a second one-way valve and a fourth solenoid valve are connected to the tube body of the boost pipe, and a carbon dioxide generator is connected to one side of the boost pipe.

[0016] The carbon dioxide conversion and purification method based on membrane separation uses a carbon dioxide conversion and purification device based on membrane separation, and comprises the following steps: Step 1: After being dried, degreased and heated, the exhaust gas enters the second tank through the exhaust gas inlet pipe, the intake manifold and the intake branch pipe. The first separation membrane adsorbs gases other than carbon dioxide and allows carbon dioxide gas to pass through. The second separation membrane allows carbon dioxide gas to pass through and blocks other gases. Step 2: The carbon dioxide gas obtained by membrane separation in the first tank body enters the cavity at the bottom of the second tank body through the top pipe and the bottom pipe, and then enters the mixing tank through the gas outlet connecting pipe. When the carbon dioxide gas flows through the gas outlet connecting pipe, the amount of the circulating carbon dioxide gas is detected by a carbon dioxide detection spectrometer, and then the amount of hydrogen required for conversion is calculated by a prediction model; Step 3: The flow meter detects the amount of hydrogen flowing in the hydrogen inlet pipe body, calculates the amount of hydrogen required for conversion through the prediction model, and finally controls the opening and closing degree of the third solenoid valve through the controller based on the detected amount of hydrogen to increase or decrease the amount of hydrogen flowing in the hydrogen inlet pipe body; Step 4: Carbon dioxide gas and hydrogen react in a carbon dioxide converter to obtain methanol, water vapor and excess hydrogen, wherein methanol and water vapor are condensed into a mixture of methanol and water through a cooler, and a gas-liquid separator separates the mixture of methanol and water and excess hydrogen into gas and liquid, and the excess hydrogen after separation enters the hydrogen inlet pipe for reuse, and the mixture of methanol and water after separation is finally distilled and separated into methanol and water through a distiller to purify methanol; Step 5: During the conversion and purification process of carbon dioxide, the air pressure inside the exhaust gas inlet pipe is detected in real time through the first pressure sensor. When the air pressure inside the exhaust gas inlet pipe is lower than the threshold, the controller controls the opening and closing degree of the fourth solenoid valve, thereby adding a certain pressure of carbon dioxide gas to the exhaust gas inlet pipe to ensure that the pressure value of the exhaust gas entering the carbon dioxide separation device is within the set range value, so as to improve production efficiency.

[0017] Among them, the steps for establishing the prediction model in step 3 are: Step 1: Obtain several groups of carbon dioxide gas amounts entering the carbon dioxide converter, establish a carbon dioxide gas amount set, and then obtain the amount of hydrogen required for the carbon dioxide gas to be completely reacted under each group of carbon dioxide gas amounts, and establish a hydrogen reaction amount set; Step 2: Linearly fit the carbon dioxide gas amount set and the hydrogen reaction amount set to obtain a prediction function, and input the carbon dioxide amount to be reacted into the prediction function to obtain the hydrogen amount to be reacted; Step 3: Set the margin coefficient, the range of the margin coefficient is 1.05-1.2; Step 4: Multiply the amount of hydrogen to be reacted by the surplus coefficient to obtain the amount of hydrogen to be added.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The carbon dioxide conversion and purification equipment and method based on membrane separation are provided with a plurality of carbon dioxide separation devices, wherein each carbon dioxide separation device comprises a first separation membrane and a second separation membrane. The first separation membrane adsorbs the remaining gases in the exhaust gas except carbon dioxide gas, and allows the carbon dioxide gas to pass through. The second separation membrane only allows the carbon dioxide gas to pass through, and blocks other gases, thereby achieving simultaneous treatment of the remaining exhaust gas while separating carbon dioxide, thereby achieving the absence of an additional exhaust gas treatment device to treat the remaining exhaust gas. The equipment occupies a small area and reduces investment and operating costs.

[0019] At the same time, the first tank body and the second tank body are arranged relative to each other and are detachably fixed therebetween. When the first separation membrane in the first tank body needs to be replaced, the first solenoid valve and the second solenoid valve are closed, and then the first tank body is removed and replaced. This process does not require shutdown, thereby improving the working efficiency of the system.

[0020] In addition, a pressure relief branch pipe and a second pressure sensor are provided. After the first solenoid valve and the second solenoid valve are closed, when the second pressure sensor detects that the pressure in the second tank body exceeds the threshold set by the system, the controller controls the fifth solenoid valve to open, and the high-pressure gas in the second tank body enters the exhaust gas inlet pipe through the pressure relief branch pipe for redistribution, thereby reducing the pressure in the second tank body and improving the safety of the equipment when used.

[0021] Furthermore, a carbon dioxide detection spectrometer is provided and a prediction model is established, which can change the amount of hydrogen added in real time according to the amount of carbon dioxide gas separated, reduce hydrogen waste, improve the separation effect of the equipment and increase the conversion amount of carbon dioxide.

[0022] In addition, an excess hydrogen outlet pipe and a first one-way valve are provided, and the excess hydrogen generated by conversion and purification enters the hydrogen inlet pipe through the excess hydrogen outlet pipe, thereby realizing the reuse of the excess hydrogen and reducing production costs.

[0023] In addition, a mixing tank is provided to prevent hydrogen and carbon dioxide gases from being separated and affecting conversion efficiency.

[0024] At the same time, a pressure stabilizing component is also provided, through which the gas pressure in the exhaust gas inlet pipe is kept constant, thereby increasing the separation efficiency of the carbon dioxide by the carbon dioxide separation device, thereby increasing the amount of ethanol converted and purified in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a first overall structural schematic diagram of the present invention; Figure 2 It is a second overall structural schematic diagram of the present invention; Figure 3 A detailed diagram of the carbon dioxide removal device of the present invention; Figure 4 It is a cross-sectional view of the carbon dioxide removal device of the present invention.

[0026] In the figure: 1. Carbon dioxide separation device; 101. First tank body; 102. First separation membrane; 103. Second tank body; 104. Second separation membrane; 105. Top pipe; 106. Bottom pipe; 107. First solenoid valve; 108. Second solenoid valve; 2. Air intake manifold; 201. Air intake branch pipe; 3. Waste gas inlet pipe; 4. Air outlet manifold; 401. Air outlet branch pipe; 402. Air outlet connecting pipe; 5. Mixing tank; 501. Mixed gas outlet pipe; 502. Hydrogen inlet pipe; 6. Flow meter; 7. Third solenoid valve; 8. Second Carbon oxide converter; 801, product outlet pipe; 802, cooler; 803, gas-liquid separator; 804, distiller; 805, first product outlet pipe; 806, excess hydrogen outlet pipe; 807, first non-return valve; 9, hydrogen generator; 10, carbon dioxide generator; 11, booster pipe; 12, fourth solenoid valve; 13, second non-return valve; 14, first pressure sensor; 15, carbon dioxide detection spectrometer; 171, pressure relief branch pipe; 172, fifth solenoid valve; 173, pressure relief main pipe; 174, second pressure sensor. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The high-temperature flue gas from the combustion device contains greenhouse gas carbon dioxide and various gaseous pollutants. This scheme is to separate, convert and purify the carbon dioxide in the flue gas.

[0029] Embodiment 1: Figure 1-Figure 4As shown, the present invention provides a technical solution: a carbon dioxide conversion and purification device based on membrane separation, comprising an exhaust gas inlet pipe 3 and a controller, one side of the exhaust gas inlet pipe 3 is fixedly connected to an intake main pipe 2, one side of the intake main pipe 2 is fixedly connected to at least one intake branch pipe 201, and the outlet of the intake branch pipe 201 is connected to a carbon dioxide separation device 1. If a plurality of carbon dioxide separation devices 1 are provided, the plurality of carbon dioxide separation devices 1 are arranged side by side. In this solution, the exhaust gas after dust removal is dried, degreased and heated, and then passes through the exhaust gas inlet pipe 3, the intake main pipe 2 and The air intake branch pipe 201 enters into the carbon dioxide separation device 1, and the carbon dioxide in the exhaust gas is separated by the carbon dioxide separation device 1, wherein the dust removal of the exhaust gas is achieved by a filter, and the drying, degreasing and heating of the exhaust gas are achieved by a gas treatment device. Specifically, the gas treatment device includes a dryer, an oil separator and a heat exchanger. The high-temperature exhaust gas after the dust is removed is dried by the dryer to remove moisture, and then sent to the oil separator for deoiling. The deoiled exhaust gas enters the heat exchanger for heating. At this time, the exhaust gas temperature after heat exchange is between 140 and 220 degrees Celsius.

[0030] The separated carbon dioxide enters the gas outlet main pipe 4 and the gas outlet connecting pipe 402 through the gas outlet branch pipe 401. The gas outlet connecting pipe 402 is connected to the carbon dioxide converter 8. A hydrogen inlet pipe 502 is arranged on one side of the carbon dioxide converter 8. A flow meter 6 and a third solenoid valve 7 are connected to the pipe body of the hydrogen inlet pipe 502. A hydrogen generator 9 is connected to one side of the hydrogen inlet pipe 502, wherein the hydrogen generator 9 can be a device for preparing hydrogen in the prior art or a storage bottle for storing liquid hydrogen. When the third solenoid valve 7 is opened, the hydrogen in the hydrogen generator 9 will enter the hydrogen inlet pipe 502 at a certain flow rate, and then the carbon dioxide and hydrogen entering the carbon dioxide converter 8 are converted by the catalyst in the carbon dioxide converter 8. The catalyst can be Cu / ZnO / Al2O3 loaded on a MIL-101 (Cr) carrier. The carbon dioxide converter 8 and the catalyst are both prior art and will not be repeated in this scheme.

[0031] like Figure 1As shown, a product outlet pipe 801 is fixedly connected to one side of the carbon dioxide converter 8, a cooler 802 is fixedly connected to one side of the product outlet pipe 801, a gas-liquid separator 803 is connected to one side of the cooler 802 through a first connecting pipe, a distiller 804 is connected to one side of the gas-liquid separator 803 through a second connecting pipe, and a first product outlet pipe 805 and a second product outlet pipe are fixedly connected to the distiller 804, respectively. It can be seen that carbon dioxide gas and hydrogen react in the carbon dioxide converter 8 to obtain methanol, water vapor and excess hydrogen, wherein methanol and water vapor are condensed into a mixed liquid of methanol and water through the cooler 802, and the gas-liquid separator 803 performs gas-liquid separation on the mixed liquid of methanol and water and the excess hydrogen, and the excess hydrogen after separation enters the hydrogen inlet pipe 502 for reuse, and the separated mixed liquid of methanol and water is finally distilled and separated by the distiller 804, and the methanol and water obtained by distillation and separation are discharged and collected through the first product outlet pipe 805 and the second product outlet pipe, respectively, thereby achieving purification of methanol.

[0032] like Figure 2 and Figure 3 As shown, a carbon dioxide detection spectrometer 15 is connected to the tube body of the gas outlet connecting pipe 402. Specifically, the carbon dioxide gas obtained by membrane separation in the first tank body 101 enters the cavity at the bottom of the second tank body 103 through the top tube 105 and the bottom tube 106, and then enters the mixing tank 5 through the gas outlet connecting pipe 402. When the carbon dioxide gas flows in the gas outlet connecting pipe 402, the amount of circulating carbon dioxide gas is detected by the carbon dioxide detection spectrometer 15, and then the amount of hydrogen required for conversion is calculated through the prediction model. The flowmeter 6 detects the amount of hydrogen flowing in the hydrogen inlet pipe 502, and the amount of hydrogen required for conversion is calculated through the prediction model. Based on the detected amount of hydrogen, the opening and closing degree of the third solenoid valve 7 is finally controlled by the controller to increase or decrease the amount of hydrogen flowing in the hydrogen inlet pipe 502.

[0033] like Figure 4 As shown, the carbon dioxide separation device 1 includes a first tank body 101 and a second tank body 103 which are detachably fixed together. The first tank body 101 and the second tank body 103 are respectively provided with a first separation membrane 102 and a second separation membrane 104. The first separation membrane 102 adsorbs the remaining gases in the exhaust gas except carbon dioxide gas, and allows carbon dioxide gas to pass through. The second separation membrane 104 only allows carbon dioxide gas to pass through, and blocks other gases. The first separation membrane 102 and the second separation membrane 104 are also prior arts and are not described in detail in this solution.

[0034] A second solenoid valve 108 is connected to the top of the second tank body 103, and a top tube 105 and a bottom tube 106 are fixedly connected to one side of the first tank body 101 and the second tank body 103 respectively. The top tube 105 and the bottom tube 106 are detachably fixed, and a first solenoid valve 107 is connected to the tube body of the bottom tube 106. The detachable fixation described in this scheme includes a flange connection or a threaded connection. The purpose of the detachable connection is to enable the first tank body 101 to be removed without affecting the system operation too much, so as to replace the first separation membrane 102.

[0035] Embodiment 2: When replacing the first separation membrane 102, it is necessary to close the first solenoid valve 107 and the second solenoid valve 108. In order to prevent the instantaneous excessive air pressure in the second tank body 103 from causing damage to the second tank body 103 and the second separation membrane 104 after the first solenoid valve 107 and the second solenoid valve 108 are suddenly closed, based on Embodiment 1, a pressure relief branch pipe 171 is fixedly connected to the top of the second tank body 103, and a pressure relief main pipe 173 is fixedly connected to one side of the pressure relief branch pipe 171. The pressure relief main pipe 173 is fixedly connected to the exhaust gas inlet pipe 3 via a third connecting pipe, a fifth solenoid valve 172 is connected to the pipe body of the pressure relief branch pipe 171, and a second pressure sensor 174 is connected to the top of the second tank body 103.

[0036] In this way, after the first solenoid valve 107 and the second solenoid valve 108 are closed, when the second pressure sensor 174 detects that the pressure in the second tank body 103 exceeds the threshold set by the system, the controller controls the fifth solenoid valve 172 to open, and the high-pressure gas in the second tank body 103 enters the exhaust gas inlet pipe 3 through the pressure relief branch pipe 171 for redistribution, thereby reducing the pressure in the second tank body 103 and improving the safety of the equipment when in use.

[0037] Embodiment three: In order to increase the output and to be able to fully and quickly separate, convert and purify the carbon dioxide in the exhaust gas, the amount of hydrogen added will be greater than the amount of hydrogen reacted. On the basis of embodiment one or embodiment one and embodiment two, an excess hydrogen outlet pipe 806 is fixedly connected to the top of the gas-liquid separator 803, and a first one-way valve 807 is connected to the pipe body of the excess hydrogen outlet pipe 806. The excess hydrogen generated by the conversion and purification enters the hydrogen inlet pipe 502 through the excess hydrogen outlet pipe 806, and the outlet of the excess hydrogen outlet pipe 806 is located between the third solenoid valve 7 and the hydrogen generator 9, thereby realizing the reuse of excess hydrogen and reducing production costs.

[0038] Embodiment 4: Since hydrogen and carbon dioxide have different molecular weights, in order to prevent the conversion efficiency of hydrogen and carbon dioxide gases from being affected by stratification, on the basis of Embodiment 1, Embodiment 1 and Embodiment 2 or Embodiment 1, Embodiment 2 and Embodiment 3, a mixing tank 5 is provided between the gas outlet connecting pipe 402 and the carbon dioxide converter 8, the gas outlet connecting pipe 402 and the hydrogen inlet pipe 502 are respectively fixedly connected to the mixing tank 5, the mixing tank 5 and the carbon dioxide converter 8 are fixedly connected via the mixed gas outlet pipe 501, a stirring element is provided in the mixing tank 5, the hydrogen and carbon dioxide gases in the mixing tank 5 are mixed by the stirring element, and the stirring element can be a mechanical agitator, a static mixer, a Venturi jet mixing or an ultrasonic assisted mixing.

[0039] Embodiment 5: Under a certain pressure, the separation efficiency of the carbon dioxide separation device 1 for carbon dioxide can be increased, thereby increasing the amount of ethanol converted and purified in the later stage. On the basis of Embodiment 1, Embodiment 1 and Embodiment 2, Embodiment 1, Embodiment 2 and Embodiment 3, or Embodiment 1, Embodiment 2, Embodiment 3 and Embodiment 4, a pressure stabilizing component is provided on one side of the exhaust gas inlet pipe 3, and the pressure in the exhaust gas inlet pipe 3 is kept constant by the pressure stabilizing component, wherein, Figure 1 and Figure 2 As shown, the voltage stabilizing component includes a boosting pipe 11 fixedly connected to the exhaust gas inlet pipe 3, and a first pressure sensor 14 connected to the exhaust gas inlet pipe 3. A second one-way valve 13 and a fourth solenoid valve 12 are connected to the tube body of the boosting pipe 11. A carbon dioxide generator 10 is connected to one side of the boosting pipe 11. Similarly, the carbon dioxide generator 10 can be a device for preparing carbon dioxide in the prior art or a storage bottle for storing dry ice. When the fourth solenoid valve 12 is opened, the carbon dioxide in the carbon dioxide generator 10 will enter the exhaust gas inlet pipe 3 at a certain flow rate.

[0040] In addition, the present invention also discloses a carbon dioxide conversion and purification method based on membrane separation, using the above-mentioned carbon dioxide conversion and purification equipment based on membrane separation, comprising the following steps: Step 1: After being dried, degreased and heated, the exhaust gas enters the second tank body 103 through the exhaust gas inlet pipe 3, the intake manifold 2 and the intake branch pipe 201. The first separation membrane 102 adsorbs gases other than carbon dioxide and allows carbon dioxide gas to pass through. The second separation membrane 104 allows carbon dioxide gas to pass through and blocks other gases.

[0041] Step 2: The carbon dioxide gas obtained by membrane separation in the first tank body 101 enters the cavity at the bottom of the second tank body 103 through the top tube 105 and the bottom tube 106, and then enters the mixing tank 5 through the gas outlet connecting pipe 402. When the carbon dioxide gas flows through the gas outlet connecting pipe 402, the amount of the circulating carbon dioxide gas is detected by the carbon dioxide detection spectrometer 15, and then the amount of hydrogen required for conversion is calculated by the prediction model.

[0042] Step 3: The flow meter 6 detects the amount of hydrogen flowing in the hydrogen inlet pipe 502, calculates the amount of hydrogen required for conversion through the prediction model, and finally controls the opening and closing degree of the third solenoid valve 7 through the controller based on the detected amount of hydrogen to increase or decrease the amount of hydrogen flowing in the hydrogen inlet pipe 502; The steps for establishing the prediction model described in step 2 and step 3 are: Step 1: Obtain several groups of carbon dioxide gas amounts entering the carbon dioxide converter 8, establish a carbon dioxide gas amount set (L1, L2, ..., Ln), and then obtain the amount of hydrogen required for the complete reaction of the carbon dioxide gas under each group of carbon dioxide gas amounts, and establish a hydrogen reaction amount set (H1, H2, ..., Hn). Specifically, when the carbon dioxide gas amount is L1, the hydrogen reaction amount used to completely react the carbon dioxide gas amount is H1; Step 2: Linearly fit the carbon dioxide gas amount set and the hydrogen reaction amount set to obtain a prediction function, and input the carbon dioxide amount to be reacted into the prediction function to obtain the hydrogen amount to be reacted; Step 3: Set the surplus coefficient. The range of the surplus coefficient is 1.05-1.2, and the preferred surplus coefficient value is 1.1. Step 4: Multiply the amount of hydrogen to be reacted by the surplus coefficient to obtain the amount of hydrogen to be added.

[0043] Step 4: Carbon dioxide gas and hydrogen react in the carbon dioxide converter 8 to obtain methanol, water vapor and excess hydrogen, wherein methanol and water vapor are condensed into a mixture of methanol and water through the cooler 802, and the gas-liquid separator 803 separates the mixture of methanol and water and excess hydrogen into gas and liquid, and the excess hydrogen after separation enters the hydrogen inlet pipe 502 for reuse, and the separated mixture of methanol and water is finally separated by distillation of methanol and water through the distiller 804 to achieve the purification of methanol.

[0044] Step 5: During the conversion and purification process of carbon dioxide, the air pressure inside the exhaust gas inlet pipe 3 is detected in real time through the first pressure sensor 14. When the air pressure inside the exhaust gas inlet pipe 3 is lower than the threshold value, the controller controls the opening and closing degree of the fourth solenoid valve 12, thereby adding a certain pressure of carbon dioxide gas to the exhaust gas inlet pipe 3 to ensure that the pressure value of the exhaust gas entering the carbon dioxide separation device 1 is within the set range value, so as to improve production efficiency.

[0045] When the first separation membrane 102 needs to be replaced, the first solenoid valve 107 and the second solenoid valve 108 are closed, and the second pressure sensor 174 detects the pressure in the second tank body 103 in real time. When the pressure in the second tank body 103 exceeds the threshold set by the system, the controller controls the fifth solenoid valve 172 to open, and the high-pressure gas in the second tank body 103 enters the exhaust gas inlet pipe 3 through the pressure relief branch pipe 171 for redistribution, thereby reducing the pressure in the second tank body 103 and improving the safety of the equipment during use. Finally, the first tank body 101 is dismantled.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is limited by the attached embodiments and their equivalents.

Claims

1. A carbon dioxide conversion and purification device based on membrane separation, comprising an exhaust gas inlet pipe (3) and a controller, characterized in that: One side of the exhaust gas inlet pipe (3) is fixedly connected to the intake main pipe (2), one side of the intake main pipe (2) is fixedly connected to at least one intake branch pipe (201), and the outlet of the intake branch pipe (201) is connected to the carbon dioxide separation device (1); The waste gas after dust removal is dried, degreased and heated, and then enters the carbon dioxide separation device (1) through the waste gas inlet pipe (3), the intake main pipe (2) and the intake branch pipe (201), and the carbon dioxide in the waste gas is separated by the carbon dioxide separation device (1); The separated carbon dioxide enters the gas outlet main pipe (4) and the gas outlet connecting pipe (402) through the gas outlet branch pipe (401), the gas outlet connecting pipe (402) is connected to the carbon dioxide converter (8), a hydrogen inlet pipe (502) is provided on one side of the carbon dioxide converter (8), and a hydrogen generator (9) is connected to one side of the hydrogen inlet pipe (502), and the catalyst in the carbon dioxide converter (8) converts the carbon dioxide and hydrogen entering the carbon dioxide converter (8); One side of the carbon dioxide converter (8) is fixedly connected to a product outlet pipe (801), one side of the product outlet pipe (801) is fixedly connected to a cooler (802), one side of the cooler (802) is connected to a gas-liquid separator (803) via a first connecting pipe, one side of the gas-liquid separator (803) is connected to a distiller (804) via a second connecting pipe, and the distiller (804) is respectively fixedly connected to a first product outlet pipe (805) and a second product outlet pipe; The pipe body of the gas outlet connecting pipe (402) is connected to a carbon dioxide detection spectrometer (15), and the pipe body of the hydrogen inlet pipe (502) is connected to a flow meter (6) and a third solenoid valve (7).

2. The carbon dioxide conversion and purification device based on membrane separation according to claim 1, characterized in that: The carbon dioxide removal device (1) comprises a first tank body (101) and a second tank body (103) which are detachably fixed together, wherein a first separation membrane (102) and a second separation membrane (104) are respectively arranged in the first tank body (101) and the second tank body (103); The remaining gases in the exhaust gas except the carbon dioxide gas are adsorbed by the first separation membrane (102), and the carbon dioxide gas is allowed to pass through, and the second separation membrane (104) only allows the carbon dioxide gas to pass through, and blocks other gases; The top of the second tank body (103) is connected to a second solenoid valve (108); a top tube (105) and a bottom tube (106) are fixedly connected to one side of the first tank body (101) and the second tank body (103), respectively; the top tube (105) and the bottom tube (106) are detachably fixed to each other; and a first solenoid valve (107) is connected to the tube body of the bottom tube (106).

3. The carbon dioxide conversion and purification device based on membrane separation according to claim 2, characterized in that: The top of the second tank body (103) is fixedly connected to a pressure relief branch pipe (171), one side of the pressure relief branch pipe (171) is fixedly connected to a pressure relief main pipe (173), and the pressure relief main pipe (173) is fixedly connected to the exhaust gas inlet pipe (3) via a third connecting pipe; A fifth solenoid valve (172) is connected to the body of the pressure relief branch pipe (171), and a second pressure sensor (174) is connected to the top of the second tank body (103).

4. The carbon dioxide conversion and purification device based on membrane separation according to claim 3, characterized in that: The top of the gas-liquid separator (803) is fixedly connected to an excess hydrogen outlet pipe (806), and a first one-way valve (807) is connected to the pipe body of the excess hydrogen outlet pipe (806). The excess hydrogen generated by conversion and purification enters the hydrogen inlet pipe (502) through the excess hydrogen outlet pipe (806); The outlet of the excess hydrogen outlet pipe (806) is located between the third solenoid valve (7) and the hydrogen generator (9).

5. The carbon dioxide conversion and purification device based on membrane separation according to claim 4, characterized in that: A mixing tank (5) is provided between the gas outlet connecting pipe (402) and the carbon dioxide converter (8); the gas outlet connecting pipe (402) and the hydrogen inlet pipe (502) are respectively fixedly connected to the mixing tank (5); and the mixing tank (5) and the carbon dioxide converter (8) are fixedly connected via the mixed gas outlet pipe (501); A stirring element is provided in the mixing tank (5), and the hydrogen and carbon dioxide gases in the mixing tank (5) are mixed by the stirring element to prevent the hydrogen and carbon dioxide gases from being stratified.

6. The carbon dioxide conversion and purification device based on membrane separation according to claim 5, characterized in that: A pressure stabilizing component is provided on one side of the exhaust gas inlet pipe (3), and the pressure in the exhaust gas inlet pipe (3) is kept constant by the pressure stabilizing component.

7. The carbon dioxide conversion and purification device based on membrane separation according to claim 6, characterized in that: The pressure stabilizing assembly comprises a boost pipe (11) fixedly connected to the exhaust gas inlet pipe (3) and a first pressure sensor (14) connected to the exhaust gas inlet pipe (3); a second one-way valve (13) and a fourth solenoid valve (12) are connected to the body of the boost pipe (11); and a carbon dioxide generator (10) is connected to one side of the boost pipe (11).

8. A method for converting and purifying carbon dioxide based on membrane separation, using the carbon dioxide conversion and purification device based on membrane separation according to claim 7, characterized in that: The following steps are involved: Step 1: After being dried, degreased and heated, the exhaust gas enters the second tank body (103) through the exhaust gas inlet pipe (3), the intake manifold (2) and the intake branch pipe (201); the first separation membrane (102) adsorbs gases other than carbon dioxide and allows carbon dioxide gas to pass through; the second separation membrane (104) allows carbon dioxide gas to pass through and blocks other gases; Step 2: The carbon dioxide gas obtained by membrane separation in the first tank body (101) enters the cavity at the bottom of the second tank body (103) through the top tube (105) and the bottom tube (106), and then enters the mixing tank (5) through the gas outlet connecting tube (402). When the carbon dioxide gas flows through the gas outlet connecting tube (402), the amount of the circulating carbon dioxide gas is detected by the carbon dioxide detection spectrometer (15), and then the amount of hydrogen required for conversion is calculated by the prediction model; Step 3: The flow meter (6) detects the amount of hydrogen flowing in the hydrogen inlet pipe (502), calculates the amount of hydrogen required for conversion through the prediction model, and finally controls the opening and closing degree of the third solenoid valve (7) through the controller based on the detected amount of hydrogen to increase or decrease the amount of hydrogen flowing in the hydrogen inlet pipe (502); Step 4: Carbon dioxide gas and hydrogen react in the carbon dioxide converter (8) to obtain methanol, water vapor and excess hydrogen, wherein methanol and water vapor are condensed into a mixture of methanol and water through a cooler (802), and a gas-liquid separator (803) separates the mixture of methanol and water and excess hydrogen into gas and liquid. The excess hydrogen after separation enters the hydrogen inlet pipe (502) for reuse. The separated mixture of methanol and water is finally distilled and separated into methanol and water through a distiller (804) to purify the methanol. Step 5: During the conversion and purification process of carbon dioxide, the air pressure inside the exhaust gas inlet pipe (3) is detected in real time by the first pressure sensor (14). When the air pressure inside the exhaust gas inlet pipe (3) is lower than a threshold value, the controller controls the opening and closing degree of the fourth solenoid valve (12), thereby adding a certain pressure of carbon dioxide gas to the exhaust gas inlet pipe (3), thereby ensuring that the pressure value of the exhaust gas entering the carbon dioxide separation device (1) is within a set range value, thereby improving production efficiency.

9. The carbon dioxide conversion and purification method based on membrane separation according to claim 8, characterized in that: The steps for establishing the prediction model in step 3 are: Step 1: obtaining a plurality of groups of carbon dioxide gas amounts entering the carbon dioxide converter (8) to establish a carbon dioxide gas amount set, and then obtaining the amount of hydrogen required for the complete reaction of the carbon dioxide gas under each group of carbon dioxide gas amounts to establish a hydrogen reaction amount set; Step 2: Linearly fit the carbon dioxide gas amount set and the hydrogen reaction amount set to obtain a prediction function, and input the carbon dioxide amount to be reacted into the prediction function to obtain the hydrogen amount to be reacted; Step 3: Set the margin coefficient, the range of the margin coefficient is 1.05-1.2; Step 4: Multiply the amount of hydrogen to be reacted by the surplus coefficient to obtain the amount of hydrogen to be added.

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